...wow, the opening caption covered the plotline perfectly!
You'll note Flash is wearing a more ornate outfit while Patch's clothes are the same, but mis-colored (as is her hair, which was silver/white in the previous chapter)!
The story concludes next Saturday!
Illustrated by Gil Kane, replacing Wally Wood.
The writer is unknown.
Though Flash had his own comic at this time, this three-parter appeared in the back of The Phantom's book from the same publisher, King Comics, a division of King Features Syndicate.
(All the King Comics books did this, presumably to expose their target audience to other titles they might not otherwise read.)
Interestingly, Flash's own book ran backup stories of Mandrake the Magician (who also had his own book) and Secret Agent X-9 (who didn't have a book at the time)!
The particular tale appeared in the back of King's The Phantom #19 (1966).
